Soaker hoses, the poor man’s drip system

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A Rancho Park gardener’s recent letter raised the question of whether a soaker hose might be a good alternative to adding an expensive drip irrigation system or installing bubblers to water her fruit trees.

The reader noted a column on Yvonne Savio, head of the UC Cooperative Extension’s master gardener program for Los Angeles County, who uses soaker hoses in her Pasadena garden. To Savio’s mind, there’s no one right way to get water in the ground, but for those interested in soaker hoses, she is happy to give tips.

The most common type of soaker hose is made from recycled tire rubber, though some are made of fabric (and don’t kink). The ones made from recycled tires are rough, porous and work by weeping water. The thicker they are, the more profusely they weep. Some hoses, also called soakers, will merely be solid rubber with holes poked in them. But I’m talking about rough weepers, which cost $10 to $15 in most home improvement stores, come in 25- and 50-foot lengths and vary in diameter from quarter-inch to half-inch.

Critics of this poor man’s drip irrigation observe that the hoses rarely have the same pressure throughout, so if you spread the hose to water a long hedge, the plants may grow to be shorter at the end of the hose. Maniacal pruning habits of modern gardeners tend to hide this flaw, but those using soakers could still change out their hoses periodically.

The most common objection to soakers is that minerals in our water cause hoses to calcify and clog. Savio said this problem is mitigated if the soakers are covered with mulch.

Newly planted saplings can be easily watered by hand, so the use of soakers generally starts with young trees. Fruit trees with roughly 5- to 10-foot canopies probably could be served with a 25-foot-long soaker. A larger specimen, particularly an established citrus or avocado, may need 75 to 100 feet or more. Use two 50-foot soakers, but never attached together, Savio said. This would amplify pressure problems big time. Either hook up one soaker at a time or get a dual spigot and use two hoses to feed the soakers. Some dual nozzle adapters even come with timers.

After buying a new soaker hose, remove the plastic plate with the pin-hole-sized opening at the bib end. Leaving it will prevent the hose from filling and the connection to the hose may explode from the pressure.

Set the coiled soaker in the sun and allow it to heat up. Once it is warm, gradually loosen the line. Place the capped end a foot from the root crown of small trees, two feet or more for larger ones. Gradually uncoil the soaker in circles around the trunk, with each line roughly 18 inches apart. To keep the soaker from drifting as you work, use small twigs poked in the soil as temporary guides. Try to avoid kinks, which can ruin the soaker, especially unheated ones. Once you have one or more soakers looped out to the edge of the tree canopy, and once it is cool outside, hook them up to a garden hose for a test. Turn on the spigot slowly. You will feel and see when the pressure is right. Beads of water should appear evenly on the rubber the full length of the soaker. You should not see an explosive leak or dangerous tension between soaker and hose, or between garden hose and spigot. Do not let a $10 soaker stress plumbing that cost thousands.

Run it for 10 to 15 minutes for it to begin steady dispersal. Smooth out kinks and ease out any residual torque in the hose. If your tree is already mulched, follow the line of the soaker creating a furrow so the soaker sinks to ground level. Cover it with mulch as you go. If your tree isn’t mulched, apply three inches of mulch on top. Remove the twigs used to steady the soaker as you go.

How long you run the soaker depends on the composition and moisture content of your soil, your micro-climate and your water pressure. In the foothills with sandy loam, with soil that is already well charged with water, Savio runs soakers around fruit trees for about an hour every two weeks when it is temperate and weekly when the thermometer is in the 90s. If you have dried-out soil, you will need to water longer, possibly several intermittent hourlong sessions for a couple of nights running or one all-night session if you have good infiltration.

If your soil is clay, it will hold water longer but take longer to permeate. Savio recommends watering for a shorter interval, but several times, allowing 24 hours for the irrigation to infiltrate and then repeating the process. Those gardening on clay may wish to use narrower soakers that emit more slowly.

I should acknowledge that Kazi Pitelka, a first-class Altadena orchardist, does favor bubblers. She used two bubblers, which are a bit like sprinklers that gurgle instead of spray, to fill a basin around a tree in the middle of the night. ‘I started with half an hour once a week when they were young,’ she said, and 15 years later ‘was up to an hour every 2 1/2 weeks.’ She also recommended Netafim drip irrigation.

But for those who go the soaker-hose route, there is no better way to judge the efficacy of your watering than looking at the tree from every angle. Describing citrus, Savio said, “If the leaves are cupping and turning upside-down, then they are thirsty and they’re trying to turn away from the sun.” Need I add that most established fruit trees shouldn’t need supplemental water during rainy season?

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-- Emily Green